/*******************************************
 * Copyright 2007 Aphrodite Framework for javaME .
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v2.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * Email : owner@aphroditeme.dev.java.net
 * Contributors:
 *     Kent Elton - initial API and implementation
 *******************************************/

package com.aphrodite.security;

/**
 * MD5 hash implementation
 * <p>
 * Message-Digest algorithm 5 implementation, It is really fast and optimized
 * for constrained devices
 * </p>
 */
class MD5 {
	private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd',
			'e', 'f', };

	/**
	 * Padding for Final()
	 */
	private static byte padding[] = { (byte) 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
			0, 0, 0, 0 };

	/**
	 * Turns array of bytes into string representing each byte as unsigned hex
	 * number.
	 * 
	 * @param hash
	 *            Array of bytes to convert to hex-string
	 * @return Generated hex string
	 */
	static String asHex(byte hash[]) {
		char buf[] = new char[hash.length * 2];
		for (int i = 0, x = 0; i < hash.length; i++) {
			buf[x++] = HEX_CHARS[(hash[i] >>> 4) & 0xf];
			buf[x++] = HEX_CHARS[hash[i] & 0xf];
		}
		return new String(buf);
	}

	/**
	 * @return true iff the first 16 bytes of both hash1 and hash2 are equal;
	 *         both hash1 and hash2 are null; or either hash array is less than
	 *         16 bytes in length and their lengths and all of their bytes are
	 *         equal.
	 **/
	static boolean hashesEqual(byte[] hash1, byte[] hash2) {
		if (hash1 == null)
			return hash2 == null;
		if (hash2 == null)
			return false;
		int targ = 16;
		if (hash1.length < 16) {
			if (hash2.length != hash1.length)
				return false;
			targ = hash1.length;
		} else if (hash2.length < 16) {
			return false;
		}
		for (int i = 0; i < targ; i++) {
			if (hash1[i] != hash2[i])
				return false;
		}
		return true;
	}

	/**
	 * If Final() has been called, finals is set to the current finals state.
	 * Any Update() causes this to be set to null.
	 */
	private MD5State finals;

	/**
	 * MD5 state
	 */
	private MD5State state;

	/**
	 * Class constructor
	 */
	MD5() {
		this.Init();
	}

	MD5(byte[] abyte) {
		this();
		Update(abyte);
	}

	/**
	 * Initialize class, and update hash with ob.toString()
	 * 
	 * @param ob
	 *            Object, ob.toString() is used to update hash after
	 *            initialization
	 */
	MD5(Object ob) {
		this();
		Update(ob.toString());
	}

	/**
	 * Returns 32-character hex representation of this objects hash
	 * 
	 * @return String of this object's hash
	 */
	String asHex() {
		return asHex(this.Final());
	}

	/*
	 * Update()s for other datatypes than byte[] also. Update(byte[], int) is
	 * only the main driver.
	 */

	private final void Decode(final byte buffer[], final int shift, final int[] out) {
		/*
		 * len += shift; for (int i = 0; shift < len; i++, shift += 4) { out[i]
		 * = ((int) (buffer[shift] & 0xff)) | (((int) (buffer[shift + 1] &
		 * 0xff)) << 8) | (((int) (buffer[shift + 2] & 0xff)) << 16) | (((int)
		 * buffer[shift + 3]) << 24); }
		 */

		// unrolled loop (original loop shown above)
		out[0] = ((buffer[shift] & 0xff)) | (((buffer[shift + 1] & 0xff)) << 8) | (((buffer[shift + 2] & 0xff)) << 16)
				| ((buffer[shift + 3]) << 24);
		out[1] = ((buffer[shift + 4] & 0xff)) | (((buffer[shift + 5] & 0xff)) << 8)
				| (((buffer[shift + 6] & 0xff)) << 16) | ((buffer[shift + 7]) << 24);
		out[2] = ((buffer[shift + 8] & 0xff)) | (((buffer[shift + 9] & 0xff)) << 8)
				| (((buffer[shift + 10] & 0xff)) << 16) | ((buffer[shift + 11]) << 24);
		out[3] = ((buffer[shift + 12] & 0xff)) | (((buffer[shift + 13] & 0xff)) << 8)
				| (((buffer[shift + 14] & 0xff)) << 16) | ((buffer[shift + 15]) << 24);
		out[4] = ((buffer[shift + 16] & 0xff)) | (((buffer[shift + 17] & 0xff)) << 8)
				| (((buffer[shift + 18] & 0xff)) << 16) | ((buffer[shift + 19]) << 24);
		out[5] = ((buffer[shift + 20] & 0xff)) | (((buffer[shift + 21] & 0xff)) << 8)
				| (((buffer[shift + 22] & 0xff)) << 16) | ((buffer[shift + 23]) << 24);
		out[6] = ((buffer[shift + 24] & 0xff)) | (((buffer[shift + 25] & 0xff)) << 8)
				| (((buffer[shift + 26] & 0xff)) << 16) | ((buffer[shift + 27]) << 24);
		out[7] = ((buffer[shift + 28] & 0xff)) | (((buffer[shift + 29] & 0xff)) << 8)
				| (((buffer[shift + 30] & 0xff)) << 16) | ((buffer[shift + 31]) << 24);
		out[8] = ((buffer[shift + 32] & 0xff)) | (((buffer[shift + 33] & 0xff)) << 8)
				| (((buffer[shift + 34] & 0xff)) << 16) | ((buffer[shift + 35]) << 24);
		out[9] = ((buffer[shift + 36] & 0xff)) | (((buffer[shift + 37] & 0xff)) << 8)
				| (((buffer[shift + 38] & 0xff)) << 16) | ((buffer[shift + 39]) << 24);
		out[10] = ((buffer[shift + 40] & 0xff)) | (((buffer[shift + 41] & 0xff)) << 8)
				| (((buffer[shift + 42] & 0xff)) << 16) | ((buffer[shift + 43]) << 24);
		out[11] = ((buffer[shift + 44] & 0xff)) | (((buffer[shift + 45] & 0xff)) << 8)
				| (((buffer[shift + 46] & 0xff)) << 16) | ((buffer[shift + 47]) << 24);
		out[12] = ((buffer[shift + 48] & 0xff)) | (((buffer[shift + 49] & 0xff)) << 8)
				| (((buffer[shift + 50] & 0xff)) << 16) | ((buffer[shift + 51]) << 24);
		out[13] = ((buffer[shift + 52] & 0xff)) | (((buffer[shift + 53] & 0xff)) << 8)
				| (((buffer[shift + 54] & 0xff)) << 16) | ((buffer[shift + 55]) << 24);
		out[14] = ((buffer[shift + 56] & 0xff)) | (((buffer[shift + 57] & 0xff)) << 8)
				| (((buffer[shift + 58] & 0xff)) << 16) | ((buffer[shift + 59]) << 24);
		out[15] = ((buffer[shift + 60] & 0xff)) | (((buffer[shift + 61] & 0xff)) << 8)
				| (((buffer[shift + 62] & 0xff)) << 16) | ((buffer[shift + 63]) << 24);
	}

	private byte[] Encode(int input[], int len) {
		int i, j;
		byte out[];

		out = new byte[len];

		for (i = j = 0; j < len; i++, j += 4) {
			out[j] = (byte) (input[i] & 0xff);
			out[j + 1] = (byte) ((input[i] >>> 8) & 0xff);
			out[j + 2] = (byte) ((input[i] >>> 16) & 0xff);
			out[j + 3] = (byte) ((input[i] >>> 24) & 0xff);
		}

		return out;
	}

	/**
	 * Returns array of bytes (16 bytes) representing hash as of the current
	 * state of this object. Note: getting a hash does not invalidate the hash
	 * object, it only creates a copy of the real state which is finalized.
	 * 
	 * @return Array of 16 bytes, the hash of all updated bytes
	 */
	synchronized byte[] Final() {
		byte bits[];
		int index, padlen;
		MD5State fin;

		if (finals == null) {
			fin = new MD5State(state);

			int[] count_ints = { (int) (fin.getCount() << 3), (int) (fin.getCount() >> 29) };
			bits = Encode(count_ints, 8);

			index = (int) (fin.getCount() & 0x3f);
			padlen = (index < 56) ? (56 - index) : (120 - index);

			Update(fin, padding, 0, padlen);
			Update(fin, bits, 0, 8);

			/* Update() sets finals to null */
			finals = fin;
		}

		return Encode(finals.getState(), 16);
	}

	/**
	 * Initialize MD5 internal state (object can be reused just by calling
	 * Init() after every Final()
	 */
	synchronized void Init() {
		state = new MD5State();
		finals = null;
	}

	private final void Transform(final MD5State md5state, final byte buffer[], final int shift, final int[] decode_buf) {
		int[] state = md5state.getState();
		int a = state[0], b = state[1], c = state[2], d = state[3], x[] = decode_buf;

		Decode(buffer, shift, decode_buf);

		/* Round 1 */
		a += ((b & c) | (~b & d)) + x[0] + 0xd76aa478; /* 1 */
		a = ((a << 7) | (a >>> 25)) + b;
		d += ((a & b) | (~a & c)) + x[1] + 0xe8c7b756; /* 2 */
		d = ((d << 12) | (d >>> 20)) + a;
		c += ((d & a) | (~d & b)) + x[2] + 0x242070db; /* 3 */
		c = ((c << 17) | (c >>> 15)) + d;
		b += ((c & d) | (~c & a)) + x[3] + 0xc1bdceee; /* 4 */
		b = ((b << 22) | (b >>> 10)) + c;

		a += ((b & c) | (~b & d)) + x[4] + 0xf57c0faf; /* 5 */
		a = ((a << 7) | (a >>> 25)) + b;
		d += ((a & b) | (~a & c)) + x[5] + 0x4787c62a; /* 6 */
		d = ((d << 12) | (d >>> 20)) + a;
		c += ((d & a) | (~d & b)) + x[6] + 0xa8304613; /* 7 */
		c = ((c << 17) | (c >>> 15)) + d;
		b += ((c & d) | (~c & a)) + x[7] + 0xfd469501; /* 8 */
		b = ((b << 22) | (b >>> 10)) + c;

		a += ((b & c) | (~b & d)) + x[8] + 0x698098d8; /* 9 */
		a = ((a << 7) | (a >>> 25)) + b;
		d += ((a & b) | (~a & c)) + x[9] + 0x8b44f7af; /* 10 */
		d = ((d << 12) | (d >>> 20)) + a;
		c += ((d & a) | (~d & b)) + x[10] + 0xffff5bb1; /* 11 */
		c = ((c << 17) | (c >>> 15)) + d;
		b += ((c & d) | (~c & a)) + x[11] + 0x895cd7be; /* 12 */
		b = ((b << 22) | (b >>> 10)) + c;

		a += ((b & c) | (~b & d)) + x[12] + 0x6b901122; /* 13 */
		a = ((a << 7) | (a >>> 25)) + b;
		d += ((a & b) | (~a & c)) + x[13] + 0xfd987193; /* 14 */
		d = ((d << 12) | (d >>> 20)) + a;
		c += ((d & a) | (~d & b)) + x[14] + 0xa679438e; /* 15 */
		c = ((c << 17) | (c >>> 15)) + d;
		b += ((c & d) | (~c & a)) + x[15] + 0x49b40821; /* 16 */
		b = ((b << 22) | (b >>> 10)) + c;

		/* Round 2 */
		a += ((b & d) | (c & ~d)) + x[1] + 0xf61e2562; /* 17 */
		a = ((a << 5) | (a >>> 27)) + b;
		d += ((a & c) | (b & ~c)) + x[6] + 0xc040b340; /* 18 */
		d = ((d << 9) | (d >>> 23)) + a;
		c += ((d & b) | (a & ~b)) + x[11] + 0x265e5a51; /* 19 */
		c = ((c << 14) | (c >>> 18)) + d;
		b += ((c & a) | (d & ~a)) + x[0] + 0xe9b6c7aa; /* 20 */
		b = ((b << 20) | (b >>> 12)) + c;

		a += ((b & d) | (c & ~d)) + x[5] + 0xd62f105d; /* 21 */
		a = ((a << 5) | (a >>> 27)) + b;
		d += ((a & c) | (b & ~c)) + x[10] + 0x02441453; /* 22 */
		d = ((d << 9) | (d >>> 23)) + a;
		c += ((d & b) | (a & ~b)) + x[15] + 0xd8a1e681; /* 23 */
		c = ((c << 14) | (c >>> 18)) + d;
		b += ((c & a) | (d & ~a)) + x[4] + 0xe7d3fbc8; /* 24 */
		b = ((b << 20) | (b >>> 12)) + c;

		a += ((b & d) | (c & ~d)) + x[9] + 0x21e1cde6; /* 25 */
		a = ((a << 5) | (a >>> 27)) + b;
		d += ((a & c) | (b & ~c)) + x[14] + 0xc33707d6; /* 26 */
		d = ((d << 9) | (d >>> 23)) + a;
		c += ((d & b) | (a & ~b)) + x[3] + 0xf4d50d87; /* 27 */
		c = ((c << 14) | (c >>> 18)) + d;
		b += ((c & a) | (d & ~a)) + x[8] + 0x455a14ed; /* 28 */
		b = ((b << 20) | (b >>> 12)) + c;

		a += ((b & d) | (c & ~d)) + x[13] + 0xa9e3e905; /* 29 */
		a = ((a << 5) | (a >>> 27)) + b;
		d += ((a & c) | (b & ~c)) + x[2] + 0xfcefa3f8; /* 30 */
		d = ((d << 9) | (d >>> 23)) + a;
		c += ((d & b) | (a & ~b)) + x[7] + 0x676f02d9; /* 31 */
		c = ((c << 14) | (c >>> 18)) + d;
		b += ((c & a) | (d & ~a)) + x[12] + 0x8d2a4c8a; /* 32 */
		b = ((b << 20) | (b >>> 12)) + c;

		/* Round 3 */
		a += (b ^ c ^ d) + x[5] + 0xfffa3942; /* 33 */
		a = ((a << 4) | (a >>> 28)) + b;
		d += (a ^ b ^ c) + x[8] + 0x8771f681; /* 34 */
		d = ((d << 11) | (d >>> 21)) + a;
		c += (d ^ a ^ b) + x[11] + 0x6d9d6122; /* 35 */
		c = ((c << 16) | (c >>> 16)) + d;
		b += (c ^ d ^ a) + x[14] + 0xfde5380c; /* 36 */
		b = ((b << 23) | (b >>> 9)) + c;

		a += (b ^ c ^ d) + x[1] + 0xa4beea44; /* 37 */
		a = ((a << 4) | (a >>> 28)) + b;
		d += (a ^ b ^ c) + x[4] + 0x4bdecfa9; /* 38 */
		d = ((d << 11) | (d >>> 21)) + a;
		c += (d ^ a ^ b) + x[7] + 0xf6bb4b60; /* 39 */
		c = ((c << 16) | (c >>> 16)) + d;
		b += (c ^ d ^ a) + x[10] + 0xbebfbc70; /* 40 */
		b = ((b << 23) | (b >>> 9)) + c;

		a += (b ^ c ^ d) + x[13] + 0x289b7ec6; /* 41 */
		a = ((a << 4) | (a >>> 28)) + b;
		d += (a ^ b ^ c) + x[0] + 0xeaa127fa; /* 42 */
		d = ((d << 11) | (d >>> 21)) + a;
		c += (d ^ a ^ b) + x[3] + 0xd4ef3085; /* 43 */
		c = ((c << 16) | (c >>> 16)) + d;
		b += (c ^ d ^ a) + x[6] + 0x04881d05; /* 44 */
		b = ((b << 23) | (b >>> 9)) + c;

		a += (b ^ c ^ d) + x[9] + 0xd9d4d039; /* 33 */
		a = ((a << 4) | (a >>> 28)) + b;
		d += (a ^ b ^ c) + x[12] + 0xe6db99e5; /* 34 */
		d = ((d << 11) | (d >>> 21)) + a;
		c += (d ^ a ^ b) + x[15] + 0x1fa27cf8; /* 35 */
		c = ((c << 16) | (c >>> 16)) + d;
		b += (c ^ d ^ a) + x[2] + 0xc4ac5665; /* 36 */
		b = ((b << 23) | (b >>> 9)) + c;

		/* Round 4 */
		a += (c ^ (b | ~d)) + x[0] + 0xf4292244; /* 49 */
		a = ((a << 6) | (a >>> 26)) + b;
		d += (b ^ (a | ~c)) + x[7] + 0x432aff97; /* 50 */
		d = ((d << 10) | (d >>> 22)) + a;
		c += (a ^ (d | ~b)) + x[14] + 0xab9423a7; /* 51 */
		c = ((c << 15) | (c >>> 17)) + d;
		b += (d ^ (c | ~a)) + x[5] + 0xfc93a039; /* 52 */
		b = ((b << 21) | (b >>> 11)) + c;

		a += (c ^ (b | ~d)) + x[12] + 0x655b59c3; /* 53 */
		a = ((a << 6) | (a >>> 26)) + b;
		d += (b ^ (a | ~c)) + x[3] + 0x8f0ccc92; /* 54 */
		d = ((d << 10) | (d >>> 22)) + a;
		c += (a ^ (d | ~b)) + x[10] + 0xffeff47d; /* 55 */
		c = ((c << 15) | (c >>> 17)) + d;
		b += (d ^ (c | ~a)) + x[1] + 0x85845dd1; /* 56 */
		b = ((b << 21) | (b >>> 11)) + c;

		a += (c ^ (b | ~d)) + x[8] + 0x6fa87e4f; /* 57 */
		a = ((a << 6) | (a >>> 26)) + b;
		d += (b ^ (a | ~c)) + x[15] + 0xfe2ce6e0; /* 58 */
		d = ((d << 10) | (d >>> 22)) + a;
		c += (a ^ (d | ~b)) + x[6] + 0xa3014314; /* 59 */
		c = ((c << 15) | (c >>> 17)) + d;
		b += (d ^ (c | ~a)) + x[13] + 0x4e0811a1; /* 60 */
		b = ((b << 21) | (b >>> 11)) + c;

		a += (c ^ (b | ~d)) + x[4] + 0xf7537e82; /* 61 */
		a = ((a << 6) | (a >>> 26)) + b;
		d += (b ^ (a | ~c)) + x[11] + 0xbd3af235; /* 62 */
		d = ((d << 10) | (d >>> 22)) + a;
		c += (a ^ (d | ~b)) + x[2] + 0x2ad7d2bb; /* 63 */
		c = ((c << 15) | (c >>> 17)) + d;
		b += (d ^ (c | ~a)) + x[9] + 0xeb86d391; /* 64 */
		b = ((b << 21) | (b >>> 11)) + c;

		state[0] += a;
		state[1] += b;
		state[2] += c;
		state[3] += d;
		md5state.setState(state);
	}

	/**
	 * Updates hash with given array of bytes
	 * 
	 * @param buffer
	 *            Array of bytes to use for updating the hash
	 */
	void Update(byte buffer[]) {
		Update(buffer, 0, buffer.length);
	}

	/**
	 * Updates hash with a single byte
	 * 
	 * @param b
	 *            Single byte to update the hash
	 */
	void Update(byte b) {
		byte buffer[] = new byte[1];
		buffer[0] = b;

		Update(buffer, 1);
	}

	void Update(byte buffer[], int length) {
		Update(this.state, buffer, 0, length);
	}

	/**
	 * Plain update, updates this object
	 */

	void Update(byte buffer[], int offset, int length) {
		Update(this.state, buffer, offset, length);
	}

	/**
	 * Update buffer with a single integer (only & 0xff part is used, as a byte)
	 * 
	 * @param i
	 *            Integer value, which is then converted to byte as i & 0xff
	 */

	void Update(int i) {
		Update((byte) (i & 0xff));
	}

	/**
	 * Updates hash with the bytebuffer given (using at maximum length bytes
	 * from that buffer)
	 * 
	 * @param stat
	 *            Which state is updated
	 * @param buffer
	 *            Array of bytes to be hashed
	 * @param offset
	 *            Offset to buffer array
	 * @param length
	 *            Use at maximum `length' bytes (absolute maximum is
	 *            buffer.length)
	 */
	final void Update(final MD5State stat, byte buffer[], int offset, int length) {
		int index, partlen, i, start;
		finals = null;

		/* Length can be told to be shorter, but not inter */
		if ((length - offset) > buffer.length)
			length = buffer.length - offset;

		/* compute number of bytes mod 64 */

		index = (int) (stat.getCount() & 0x3f);
		stat.setCount(state.getCount() + length);// count += length;

		partlen = 64 - index;

		if (length >= partlen) {
			// update state (using only Java) to reflect input

			int[] decode_buf = new int[16];
			if (partlen == 64) {
				partlen = 0;
			} else {
				for (i = 0; i < partlen; i++)
					stat.buffer[i + index] = buffer[i + offset];
				Transform(stat, stat.buffer, 0, decode_buf);
			}
			for (i = partlen; (i + 63) < length; i += 64) {
				Transform(stat, buffer, i + offset, decode_buf);
			}
			index = 0;
		} else
			i = 0;

		/* buffer remaining input */
		if (i < length) {
			start = i;
			for (; i < length; i++) {
				stat.buffer[index + i - start] = buffer[i + offset];
			}
		}
	}

	/**
	 * Update buffer with given string. Note that because the version of the
	 * s.getBytes() method without parameters is used to convert the string to a
	 * byte array, the results of this method may be different on different
	 * platforms. The s.getBytes() method converts the string into a byte array
	 * using the current platform's default character set and may therefore have
	 * different results on platforms with different default character sets. If
	 * a version that works consistently across platforms with different default
	 * character sets is desired, use the overloaded version of the Update()
	 * method which takes a string and a character encoding.
	 * 
	 * @param s
	 *            String to be update to hash (is used as s.getBytes())
	 */
	void Update(String s) {
		byte chars[] = s.getBytes();
		Update(chars, chars.length);
	}

	/**
	 * Update buffer with given string using the given encoding. If the given
	 * encoding is null, the encoding "ISO8859_1" is used.
	 * 
	 * @param s
	 *            String to be update to hash (is used as
	 *            s.getBytes(charset_name))
	 * @param charset_name
	 *            The character set to use to convert s to a byte array, or null
	 *            if the "ISO8859_1" character set is desired.
	 * @exception java.io.UnsupportedEncodingException
	 *                If the named charset is not supported.
	 */
	void Update(String s, String charset_name) throws java.io.UnsupportedEncodingException {
		if (charset_name == null)
			charset_name = "ISO8859_1";
		byte chars[] = s.getBytes(charset_name);
		Update(chars, chars.length);
	}

}
